InSb nanoscale crystal islands were grown on a Se-terminated GaAs subs
trate by molecular beam epitaxy (MBE). In situ synchrotron radiation p
hotoelectron spectroscopy studies for InSb island formation on this su
rface show that Sb atoms do not chemisorb directly onto the Se-termina
ted GaAs surface. The In overlayer is grown in a nearly laminar mode o
n the Se-terminated GaAs, and then Sb atoms diffuse across this surfac
e until they bond to In or desorb. Consequently, InSb islands are form
ed. This islanding phenomenon is associated with the energy difference
between the surface free energy of InSb and that of the Se-terminated
surface, and with the strain energy due to the high lattice-mismatch
stress. Furthermore, it is found that the InSb islands grown at 200 de
grees C have an average size of 30 nm and a density of the order of 10
(10) cm(-2).